~ Integrated Approach to Data

AIX ntp Configuration

The NTP daemon can not only adjust its own computer’s system time. Additionally, each daemon can be a client, server, or peer for other NTP daemons:

As client it queries the reference time from one or more servers.

As server it makes its own time available as reference time for other clients.

As peer it compares its system time to other peers until all the peers finally agree about the “true” time to synchchronize to.

These features can be used to set up a hierarchical time synchronization structure. The hierarchical levels of the time synchronization structure are called stratum levels. A smaller stratum number means a higher level in the hierarchy structure. On top of the hierarchy there is the daemon which has the most accurate time and therefore the smallest stratumnumber.

By default, a daemon’s stratum level is always one level below the level of its reference time source. The top level daemon often uses a radio clock as reference time source. By default, radio clocks have a stratum number of 0, so a daemon who uses that radio clock as reference time will be a stratum 1 time server, which has the highest priority level in the NTP hierarchy. In large networks it is a good practice to install one ore more stratum 1 time servers which make a reference time available to several server computers in each department. Thus the servers in the departments become stratum 2 time servers which can be used as reference time source for workstations and other network devices of the department.

Unlike in telecom applications where the word stratum is used e.g. to classify oscillators according to their absolute accuracy, the term stratum in the NTP context does not indicate a certain class of accuracy, it’s just an indicator of the hierarchy level.